Concrete mixer



July 21, 1959 E. D. HUNKINS 2,895,722

CONCRETE MIXER Filed Aug. 20, 195e s Sheets-Sheet 1 a, M 41W; Ma

July 21, 1959 E. D. HUNKINS' 2,895,722

CONCRETE MIXER Filed Aug; 20, 1956 s Sheets-Sheet 2 FIG.3- v

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E., D. HUNKINS CONCRETE MIXER Jul 'zl; 1959 3 Sheets-Sheet 3 Filed Aug. 20, 1956 FIGJO fvns'ywz Ens-25770. #wvk/ms M WW; Maw

United States Patent, Ofiice CONCRETE MIXER Everett lD. Hunkins, University City, Mo. Application August 20, 1956, Serial No. 605,026

'7 Claims. (Cl. 259-164) This invention relates in general to concrete mixers, and in particular, to concrete mixers of the horizontal type. The present invention is embodied primarily in concrete mixers of relatively large capacity, in the order of six to eight cubic yards or greater, but may be utilized .to advantage in concrete mixers of smaller size.

In the past, concrete mixers have been rotatably supported by relatively heavy and expensive means on the rear platform of a truck. Substantial numbers of inclined conical type drums were provided with a heavy expensive bearing or ring which encircled the rear of the mixer and which was supported by plurality of small .rollers, usually two ,in number, near the platform of the truck. Prior mixers in general have been provided with filling openings which have external doors which tend to leak no matter how tightly the door is pressed inwardly against the opening. In addition, prior mixers have been provided with discharge openings which were covered by relatively expensive and complicated cover members actuated by hand wheels and/or mechanical linkages. In addition, the chutes for receiving the discharged material left much to be desired both in manufacture and in operation due to the fact that some chutes were not located directly beneath the discharge opening in all positions of the chute.

One of the principal objects of the present invention is to provide a chain suspension .for supporting the rear end of a heavy concrete mixer. Another object is to provide a suspension for the rear hub of a mixer which allows said hub to rotate and to move within limits in a lateral direction to reduce strain placed on the frame due to the truck being driven upon uneven terrain during travel or at the construction site. Another object is to provide a chain suspension for the rear hub of a heavy mixer, the ends of said chain being secured .to pivotally mounted brackets retained in an upstanding frame member.

Another object of the present invention is .to provide an inside door for the filling opening which is adapted to move within the mixer drum to its opened and closed positions, so that in its closed position the weight of the concrete within the drum tends to close the inside door more tightly thereby lessening the possibility of leakage. Another object is to provide a simple inside door construction which allows the door to be moved completely out of the way so as to expose the entire area of the filling opening.

Another object is to provide a :novel chute suspension wherein the chute is horizontally rotatably mounted directly beneath the discharge opening and is adapted to rotate about a vertical axis so as to always remain directly below said opening. Another object is to provide suitable flexible-connections so that chute extensions may may be provided to direct the concrete to points rela- -tively distant from the mixer itself.

the line 55 of Fig. 3,

scribed and claimed.

Another object is to provide a rear screw or blade in the discharge opening of a mixer, said screw being made from a plurality of rods stacked together and fanned out a few degrees from one another, and then secured tothe inside of said hub.

A still further object is to provide a rear rotary door and mount therefor, said door being pivotally mounted with respect to the frame and adapted to rotate with the drum.

These and other objects and advantages will become apparent hereinafter.

The present invention is embodied in a concrete mixer having a chain suspension for rotatably supporting the rear portion of the mixing drum. The invention is also found in the provision of an inside door which covers the loading opening in the drum, in the chute suspension, in 'the rear screw and process of making same, and in the rear rotary door and mount therefor.

The invention also consists in the parts and in the arrangements and combinations of parts hereinafter de- In the accompanying drawings which form .part of this specification and wherein like numerals and symbols refer to like parts wherever they occur:'

Fig. 1 is a side elevational view of a mixer embodying the present invention mounted on a suitable heavy-duty truck,

Pig. 2 is a rear elevational view thereof showing the chute in its extended position,

Fig. 3 is a fragmentary rear view, partly in cross section, of the chain suspension after the rear cover plate and other parts have been removed for clarity,

Fig. 4 is a horizontal cross-sectional view taken along the line 4-4 of Fig. 3,

Pig. 5 is a vertical cross-sectional view taken along 'mechanism for raising and lowering the inside track,

Fig. 10 is a horizontal cross-sectional view taken along the line 1010 of Fig. 3 showing the rear screw within the hub,

Fig. 11 is a top plan view of the chute by itself,

Fig. 12 is a fragmentary side elevational view of the rear rotary door and actuating linkage, and

Fig. 13 is a side view of a typical bar used to make the rear screw.

Referring now to the drawings in detail, it will be seen that the embodiment of the invention which has been illustrated comprises a relatively large and heavy concrete mixer 1 suitably mounted on a frame 2 of a truck or prime mover 3 having means 4 thereon for rotating said drum. As best shown in Figs. 1 and 2, the mixer 1 comprises a drum 5 of the heavy horizontal type having a curved or cylindrical wall 6 with a front end wall 7 and a rear end wall 8. The front end wall 7 is of relatively heavy material and is rotatably mounted at its center, through which passes the axis 9 of said drum 5. The front wall 7 has no openings therein for material. The rear end wall 8 is curved slightly but is substantially 9 having a discharge opening 11 therethrough. A screw 2,895,722 1 Patented July 21, 1959 i convey material outwardly or rearwardly through the hub 10 when the drum 5 is rotated. The drum 5 is pro vided with internal vanes and buckets, not shown, which agitate the concrete and direct the mixed concrete into the hub 10. The frame 2 comprises the various fixed supporting members which rotatably hold said drum 5 and also includes the various covering members and the like which support the rear door and the chute, as will be explained hereinafter.

The cylindrical wall 6 is ing 13 of any suitable geometric shape circumscribed by a slanting rim 14 which forms a funnel for directing materials into the drum 5 prior to their being mixed. The inner or lower edge 15 of the rim 14 is positioned slightly inwardly of the wall 6. An inside door 16 having a recess 17 and handle 18 therein covers or closes the opening 13 from the inside. The door 16 is slidably mounted on a track 19 having a pair of substantially parallel track members 20 and 21 positioned longitudinally of said drum 5 parallel to the axis thereof and preferably in alignment with the opposite edges of the inner ends 15 of the rim 14. The door 16 is slightly larger in size than the opening 13 or space within the edges of the rim. A bar 22 connects the rear ends of the track memor blade 12 is fixedly secured within the hub so as to' 31 is suspended by means of end pins 35 mounted in provided with a loading openbers 20 and 21 and is provided with outwardly extending means 23 for raising and lowering said rear ends of the track 19. In practice, the means 23 comprises a screw 24 and crank 25 arrangement which can be operated by the operator standing on the ladder 26 at the rear of the drum 5. The forward ends of the track members 20 and 21 are pivotally and adjustably mounted to a front bracket 27. The adjustment means 28 includes screws 29 for moving the front ends of the track members 20 and 21 laterally and toward and away from the wall 6 of the drum 5.

As best shown in Fig. 7, the inside door 16 is biased against the edges 15 of the rim 14 by means of the track 19. When the drum 5 is rotated so that the filling opening 13 is rotated to its lower positions, the weight of the material being mixed tends to close the inside door 16 and reduce the likelihood of leakage. The inside door 16 is opened only when the drum has stopped rotating and is in need of another charge. Preferably, the drum 5 should be stopped when the opening 13 is in its highest position as shown in Fig. 1. To open the inside door 16,

the operator rotates the crank 25 to force the rear end of the track 19 downwardly thereby moving the door slightly downwardly and breakingthe sealing relationship with the rim 14. The operator then grasps the handle 18 and pushes or slides the door forwardly along the track 19 until the door 16 completely uncovers the opening 13 as shown by the dotted lines in Fig. 6. The drum 5 can then be charged with material after which. the operator grasps the handle 18 and slides the door rearwardly until the opening 13 is covered. He then rotates the crank 25 which raises the track 19 thereby forcing the door 16 tightly against the rim 14. p i

The adjustment means 28 at the forward end. of the track 19 is provided for initial adjustment of the parts so that the entire periphery of the inside door 16 is biased against the rim 14 with substantially the same force. The adjustment means 28, which is used to raise and lower the forward end of the track 19 is also used to compensate for any wear which might have taken place in the track, inside door, or rim, or to re-align the parts laterally.

The rear wall 8 of the drum 5 is provided with a hub 10 concentrically secured thereto, preferably by welding, along the axis 9 ofsaid drum 5. The rear hub 10 extends rearwardly of said rear wall 8 and is held in a chain suspension 30 having a chain 31 with a plurality of rollers 32 therein rotatably mounted on pins 33 connecting the links 34, which are preferably smaller in width than the diameter of the rollers 32. The chain side brackets 36 which are pivotally supported by support blocks 37 secured to upstanding members 38, preferably made from channel steel. The upper or end rollers 32 mounted on the end pins 35 contact the hub 10 substantially at the opposite ends of a horizontal diametral line through said hub 10. The side brackets 36 are of U-shape and a retainer 39 secured to each support block 37 and extending upwardly within the pocket of each side bracket 36 prevents the side brackets 36 from slipping off of said support blocks 37.

In their normal position, the side brackets 36 slant slightly inwardly toward each other and are so retained by means of the leaf springs 40 suitably secured to the channel members 38 by means of bolts 41. The leaf springs 40 bias the side brackets 36 away from the channel members 38. The drum 5 is lowered into position so that the rear hub 10 thereof is supported by the chain 31 over the major portion of its lower half. The great weight of the drum 5, either unloaded or loaded with concrete, holds the hub 10 securely in place in the'chain suspension 30. Should the truck 3 encounter rough terrain during unloading or in travel, the hub 10 is free to move laterally between the side members 38 within limits. The hub 10 is not physically attached to the chain 31 but simply rests therein by gravity so that 'it can at all times assume its normal position, and the chain 31 is simply suspended between the side brackets 36. The leaf springs 40 tend to center the hub 10 between the upstanding supports 38. The chain suspension 30 is completely-enclosed by frame or covering members including a rear cover plate 42 which prevents damages .from sand, gravel, and other matter which might otherwise-become lodged between the various parts. Oiling means 43 are also provided for the various parts and portion. The bottom 46 rotates about a vertical axis 48 with reference to a horizontal platform 49 held in position by three relatively heavy braces 49a secured to the frame 2. Chute extensions 50 and 51 are serially secured to the receiver 45 at the open side thereof by means of a horizontally positioned hinge 52 and flexible side connections 53 and a flexible bottom connection 54. A

hydraulic cylinder 55 pivotally mounted on the frame 2 pivotally secured to the first chute extension 50 is provided for raising and lowering the end of the chute 44,

the horizontal pivotal movement being accomplished manually. The receiver 45 remains beneath the opening 11.- at all times and the operator may easily rotate the chute 44 anywhere within substantially behind the truck 3 and use the hydraulic cylinder 55 to raise or lower the end of the chute 44 for directing the mixed concrete to the desired spot. As best shown in Fig. 2, the chute 44 is provided with a first extension 50 and a second extension 51 serially connected thereto, but may be pro vided with additional extensions if desired depending upon the distance which the mixed concrete must travel.

One end of the hydraulic cylinder 55 is pivotally mounted on the frame 2 and the other end is preferably pivotally secured to the remote or lower end of the first extension 50. During travel, the second extension 51 is pivoted upwardly 180 about the hinge 56 so that its upper edge as shown is in contacting relation with the upper edge of the first extension 50 and its end 57 is adjacent to the receiver 45. The dotted lines in Fig. 2 show how the hydraulic cylinder 55 is adapted to raise the extension 50.

The discharge opening 11 in the hub 10 is normally closed except during a pouring operation. The discharge opening 11 is covered by a circular rear door 58 which is adapted to abut against the rear of the hub 10, which edge is inch thick and is provided with a collar. The

rear door 58 rotates witht the drum 5 so there is no movement between said door 58 and said hub which maintained in leakproof relation. The door 58 is rotatably mounted on a door holder 59 which is pivotally mounted to a bracket 60 secured to the stationary frame or rear cover plate 42 for the chain suspension directly above the hub 10. A suitable mechanical linkage 61 is provided so that the operator can rotate the crank 62 as he stands on the ground to open and close the rear door 58. This mechanical linkage 61 includes a crank 62 and suitable upstanding members 63 as best shown in Fig. 12 which extend upwardly along the outside of the channel members 38 and are operatively connected to a horizontal bar 64 which forms part of and to which is secured the pivoted rear door holder 59.

The rear screw or blade 12 is made from a plurality of identical rods 65 as best shown in Fig. 13 fanned out diametrically across the hub 10. Each rod 65 has a central hole 66 therein which has been aligned with the other center holes 66 so that a bar 67 can be inserted through said holes. The bar 67 has a head 68 at one end and a nut 69 on the other end for keeping the rods 65 in tight frictional contact. The rods 65 so stacked are then twisted or fanned out a constant and predetermined number of degrees from each other, but are maintained in slight overlapping relationship at their ends, to form the twisted blade 12 which fits into the near hub 10 and directs concrete from the drum 5 to the receiver 45 of the chute 44. The rods 65 are welded at their ends to the inner surface of the hub 10. The rods 65 are of relatively heavy steel of substantially rectangular crosssection. The blade 12 must be heavy so as to withstand the impact forces placed thereon by relatively large quantities of concrete being thrown thereagainst from the buckets within the drum 5 when the concrete is being poured. Eventually, all concrete within the drum 5 passes through the hub 10 and must be supported by the blade 12. The use of rods which are fanned to form the blade solves a difficult and expensive if not an impossible fabrication problem created by the fact that the blade must be heavy and rugged to withstand the high forces, including impact forces, placed thereon in operation.

In practice, the following sizes for various parts have been found to give satisfactory results: a hub 10 with a Wall thickness of inch, rollers 32 which are 3 /2 inches in diameter, leaf springs 40 which are 3 inches wide, channel or side members 38 which are made from 6 inch channel steel and which face inwardly toward each other with their fiat central portions about 31% inches apart, rods 65 which are 16 /2 inches long, inch high, and A: inch thick. The rollers 32 should be rotatably mounted on the pins 33 with bearings therebetween to reduce friction. The foregoing dimensions are given merely as matters of illustration, and not by way of limitation, to enable the reader to more fully appreciate the size of materials which have been used satisfactorily in 8 ton concrete mixers.

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

What I claim is:

1. A material mixer comprising a rotatable mixing drum, said drum having a hub at one end thereof, means for rotatably supporting the opposite end of said drum, and means for rotatably supporting said hub, said latter means comprising a chain fixedly secured to and positioned between stationary supporting means on said mixer, said hub supported in a rotatable position by said chain.

2. A material mixer comprising a rotatable mixer drum, said drum having a hub at one end with a discharge opening therethrough, means for rotatably supassent porting the end of said opposite to said hub, andmeans for rotatably supporting said hub, said latter means comprising a pair of stationary support members, a rela" tively stationary chain fixedly secured to and positioned between said supportmembers with its center positioned below its ends, said hub supported in an elevated rotatable position by said chain.

3. A material mixer comprising a rotatable mixer drum having a substantially horizontal axis, said drum having front and rear end walls, means for rotatably supporting said front end wall, said rear end wall having a hub therein with a discharge opening therethrough, an upstanding support member on either side of said hub, a chain suspended between said support members with its center portion positioned below its supported ends, said chain having rollers therein, said hub adapted to be held in an elevated rotatable position by said rollers in said chain.

4. A material mixer comprising a rotatable mixer drum having a substantially horizontal axis, said drum having upstanding front and rear end walls, means for rotatably supporting said front end wall, said rear end wall having a hub therein with a discharge opening therethrough, a pair of upstanding support members, one on each side of said hub, side brackets pivotally mounted on said support members, a chain suspended between said side brackets, said chain having a plurality of rollers therein, said hub adapted to be held in an elevated rotatable position by said rollers in said chain.

5. A material mixer comprising a rotatable mixer drum having a substantially horizontal axis, said drum having upstanding front and rear end Walls, means for rotatably supporting said front end wall, said rear end wall having a circular hub therein with a discharge opening therethrough along the axis of said drum, a pair of upstanding support members, one on each side of said hub, said brackets pivotally mounted on said support members and adapted to move toward and away from said support members, means normally biasing said side brackets away from said support members, a chain having a plurality of rollers therein suspended between said side brackets, said circular hub supported by said rollers in said chain along its lower portion, said hub adapted to move laterally within limits between said upstanding supports.

6. In a mixer for concrete and the like, a rotatable mixer drum having a curved wall, said wall having a loading opening therein with an internal rim therearound, a door positioned inside of said drum for covering and uncovering said opening, said inside door being slidably mounted on a track secured to and positioned within said drum, said track positioned substantially parallel to the axis of said drum, control means extending exteriorly of said drum for moving one end portion of said track toward and away from said drum, said opposite end portion of said track being pivotally and adjustably mounted on means secured to said drum, said control means adapted to move said door into tight contacting relation with said rim for tightly closing said opening.

7. In a mixer for concrete and the like, a rotatable mixer drum having a curved wall, said wall having a filling opening therein with a sloping rim therearound, a door positioned inside of said drum for covering and uncovering said opening, said inside door being slidably mounted on a track secured to and positioned within said drum, said track positioned substantially parallel to the axis of said drum, a crank extending exteriorly of said drum for moving one end portion of said track toward and away from said drum, said opposite end portion of said track being pivotally and adjustably mounted on means secured to the wall of said drum opposite the opening from said crank, said crank adapted to move said door into tight contacting relation with said rim for tightly closing said opening.

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